1. Field of the Invention
The present invention relates to a purging apparatus and a purging method, and more particularly to a purging apparatus and a purging method for purging a container having an openable lid by supplying and discharging a clean gas to and from the inside of the container.
2. Description of the Related Art
Conventionally a SMIF (standard mechanical interface) pod is a known example of a substrate holding container for transporting and storing substrates, such as photomasks, glass substrates, wafers, and reticles, in semiconductor manufacturing environments. The SMIF pod has a pod cover and an openable lid. During transport and storage, the pod cover is closed by the lid such that the SMIF pod is sealed and contaminants are prevented from entering the pod.
A latch mechanism is provided to lock the lid to the pod cover. Thus, the lid is locked in place with the latch mechanism when a substrate is transported or stored. When a substrate is to be removed, the latch mechanism is released such that the lid can be removed from the pod cover.
Also known is an opening/closing device configured to automatically open and close a SMIF pod when a substrate is loaded into or removed from the SMIF pod. The opening/closing device has a stage on which the SMIF pod is placed and an elevator driving mechanism for driving the stage up and down. The stage is provided with a pin for positioning the SMIF pod in a prescribed position. The opening/closing device also has a latch controlling mechanism for controlling the latch mechanism, so as to lock and release the latch mechanism.
An opening/closing device inside a clean stocker is described in Japanese Laid-open Patent Publication No. 2008-30914.
When a pod is placed on the stage, the opening/closing device first releases the latch of the latch mechanism using the latch controlling mechanism. The elevator driving mechanism then lowers the stage. As a result, the lid moves downward along with the substrate. When the lid has been lowered to a prescribed position, a robot moves the substrate toward a processing apparatus. After processing, the robot returns the substrate to the stage. The elevator driving mechanism then raises the stage. As a result, the lid moves upward along with the substrate. When the lid has been fitted into the pod cover, the latch controlling mechanism engages the latch of the latch mechanism.
The opening/closing device also has a purging mechanism. The purging mechanism is a mechanism for replacing an atmosphere inside a pod with nitrogen or another inert gas. Purging suppresses the occurrence of organic contamination and chemical changes such as natural oxidation on a surface of the substrate.
The purge mechanism has a gas supply tank, a supply pipe, a discharge pipe, an on-off valve, and a flow regulating valve. The supply pipe is connected to a supply port of the pod and supplies gas from the gas supply tank to the inside of the pod. The discharge pipe is connected to a discharge port of the pod and discharges gas from inside the pod to the outside. The on-off valve and the flow regulating valve are provided on both the supply pipe and the discharge pipe as required.
After processing is finished, the substrate is placed on the lid and the substrate is raised together with the lid until the lid fits into the pod cover. The latch mechanism is then latched such that the lid is locked to the pod cover. The purge mechanism then purges the inside of the pod. As a result, a purge operation time is comparatively long and there are times when a pod containing a substrate cannot be transported to a downstream apparatus early enough to satisfy a demand.